I have afib and have been cardioverted once ~4 years ago. Own a kardia ekg and a regular blood pressure cuff. Coffee increases my pulse, but the waveform remains normal. Alcohol is the real killer, a very small amount like a beer will immediately show in ekg waveform abnormalities. Enough to get a buzz and it's a warzone let alone actually drunk. It's also surprising how long it lasts even into the hungover and no longer drunk zone. I'm not a doctor, but I would personally recommend to cut out all drinking with an occurrence of afib and yes, this is conjecture, but any sort of heart condition. I'm also not being sponsored by kardia and am creeped out by it storing my data presumably on the cloud.